Air and feed control for hammer mills



Sept. 25, 1956 Filed Feb. 17. 1954 O n A a 5 5 I x 19\ .12 2a ;7

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, Q o h o 4 3 o o o I o F INVENTOR AIR R. A. MOORE AND FEED CONTROL FOR HAMMER MILLS 2 Sheets-Sheet 1 ROBERT A. MOORE ATTORNEY Sept. 25, 1956 R. A. MOORE AIR AND FEED cou waox, FOR HAMMER MILLS 2 Sheeis-Sheet 2 Filed Feb. 17, 1954 INVENTOR ROBERT A MOORE ATTORNEY United States Patent AIR AND FEED CONTROL FOR HAMMER MILLS Robert A. Moore, Salem, Va.

Application February 17, 1954, Serial No. 410,818

Claims. (Cl. 241-186) This invention relates to an improvement in a feed control for hammer mills of the type wherein a cross bafile is adjustable in the flow of incoming material to vary the size of the impact area of the grinding chamber to result in constant suspension grinding for materials of different size and weight ground in a single mill and the primary object of the invention is to increase the efiiciency of the assembly by providing an improved form of baflle and to separate the air feed for the mill from the material feed.

Another object of the invention is to provide an improved bafile in a feed control of this character that will divide the grinding chamber of the hammer mill into two separate areas, one for primarily receiving the fed material and the other for primarily feeding air to the mill.

A further object of the invention is to provide an improved baffle in a feed control of this character that upon movement will permit the lower edge of the cross bafile to substantially follow the curvature of the throw of the hammers and the upper edge to move in a straight line along the throat of the mill.

Still another object of the invention is an improved bafiie in a feed control of this character that results in constant suspension grinding for materials of different size and weight in use but which may be moved to an inoperative position to permit the hammer mill to operate in a conventional manner.

Still a further object of the invention is to provide means for operating the baffle from the exterior of the mill so that any desired change can be made during the operation of the hammers.

Still another object of the invention is to eliminate the possibility of choking the mill in operation, power surges and mill slugging.

These and other objects of the present invention will appear as the following description thereof proceeds, and in order to more clearly understand the invention, reference may be made to the accompanying drawings in which:

Figure 1 is a vertical section through a hammer mill with the feed control and separate air feed applied thereto;

Figure 2 is an end view of the hammer mill assembly with the head portion in section on the line 22 of Figure 1; and

Figure 3 is a fragmentary section on the line 33 of Figure 2.

A feed control for hammer mills of the cross baflle type that results in suspension grinding for different materials is disclosed in the patent to Moore, 2,609,153, September 2, 1952. The continuous suspension grinding results from moving the bafile in the flow of incoming material to vary the size of the impact area of the grinding chamber. As these mills are primarily for grinding grain or the like and as the weight and size of such materials vary, it is necessary to change the relationship of parts for each type of material being ground. This invention reg 2,764,361 Patented Sept. 25, 1956 "ice lates to an improved form of bafile with a separate and distinct air feed for the mill.

In Figures 1 and 2 of the drawings there is shown a rotary hammer mill having a base 1, a motor 2, mill base 3, containing the rotating hammers 4, concave screen 5, and fan and duct 6. These are parts of a conventional hammer mill assembly and form no part of the invention. On the base 3 is mounted a mill top 7 which covers the upper throw of the hammers 4. This includes a combined hopper and inlet 8, supported by a slide link 9 on the mill top adjacent the base 3 and arranged at the front of the mill top. This combined hopper and inlet has an open throat portion adjacent the open front edge 10 of the mill top 7. Rearwardly of the front edge 10 of the mill top is an air inlet opening 11 leading by the passage 12 to the grinding chamber of the mill top.

Within the mill top and above the arc of the throw of the hammers 4 is mounted a hinged cross baffle 13 encompassing substantially the entire cross area of the same comprising a lower section 14 and an upper section 15 hingedly connected thereto as shown at 16. The baffle 13 is supported for movement by providing the outer bottom edge of the lower section 14 with lateral studs 17 movable in guide tracks 18 formed in the side walls of the top 3. These guide tracks 18 extend from the bottom edge of the inlet 8 to the rear wall of the mill top. They are preferably curved throughout most of their length to conform approximately to the arc of the throw of the hammers 4 and are positioned to provide a working clearance between the lower edge of the bafile section 14 and said hammers. A straight back ofi portion 18' terminates the tracks adjacent the back of the mill. The

hinged upper section 15 of the baffle 13 is provided at its upper corners with lateral studs 17 corresponding to the studs on the section 14 adapted to move in straight guide tracks 19 formed in the side walls of the mill top and extending downwardly and inwardly from the front edge 10. In the conventional hammer mill the grinding chamber extends from a point adjacent the bottom of the feed inlet to approximately the rear wall of the mill. Where a baflle is used in the mill top or head the area of hammer impact is restricted to form the lower edge of the hopper and inlet 8 to the lower edge of the baflie.

When mounted as described the baflle 13 may be moved to vary the area of hammer impact on the ma terial being ground in the grinding chamber for the purpose set forth and from the exterior of the mill by a long screw 20 secured to the rear face of the lower section 14 of the baffle at 21 and extending through an opening 22 in the rear of the mill top. On said rear face is mounted a casing 23 for a turn member 24 on the screw. A handle 25 is mounted thereon. For remote rotation of the screw 20 there is provided in the casing miter gears 26, one on the turn member 24 and the other at the end of a remote drive shaft 27 suitably braced at 28 and extending out of the mill pit or to a floor above and terminating in a remote control handle 29. Thus by rotating either handle 25 or 29 the screw 20 will move the baflle 13 toward or from the flow of incoming material fed from the hopper and inlet 8 and vary the size of the impact area of the hammer on the material in the grinding chamber for the purpose set forth.

In effect with this type of baflle the normal grinding chamber of the mill is divided into two sections. The section in front of the baffle plate receives only the material to be ground and as the upper section 15 cooperates with the inlet the same can be entirely filled and act as a hopper as well as a feed inlet. The air required to operate the mill is pulled through the inlet 11, passage 12, and across the rear section of the normal grinding chamber into the mill. Thus the bafiie has the dual function of maintaining suspension grinding for different type of materials in a single mill and also acts as a divider for the chambers that maintains this relationship at any set position of the baflie and during movement of the same. In the conventional hammer mill the air is fed through the front of the mill with the material. A baflle type feed control will result in suspension grinding for difierent materials upon movement of the bafiie irrespective of how the air is fed and provided there is a working clearance between the bottom edge of the baffle and are of throw of the hammers, but this type of bafile plate, mount and separate air feed has proven a more practical means for accomplishing the desired result.

With the disclosed construction the bafiie 13 can be moved completely forward cutting ofi entirely the supply of feed into the mill, or it can be retracted to substantially cut off the supply of air through the inlet 11 and passage 12 where, for instance, additional air is unnecessary as when grinding baled hay or ear corn. The mill may be even used as a conventional type hammer mill by adjusting the inlet and utilizing the protector plate 30 in the usual manner. The speed of the motor that rotates the hammers is of course under control of the mill operator and obviously may be varied if necessary after change-overs to maintain suspension grinding without choking and power surges of the mill.

I claim:

1. A feed control for hammer mills including rotating hammers, a combined hopper and material feed inlet at the top. of the mill to flow only material to be ground into the upper arc of the throw of the hammers in the same direction of rotation and at one side thereof, a movable bafile plate mounted across the top of the mill, said baffle plate comprising two hingedly connected sections, means to move the baffie plate through the mill top, means to move the lower edge of one section substantially along the curvature of the throw of the hammers, and means to move the upper edge of the other section substantially parallel with the 110w of the fed material.

2. A feed control for hammer mills including rotating hammers, a combined hopper and material feed inlet at the top of the mill to flow only material to be ground into the upper arc of the throw of the hammers in the same direction of rotation and at one side thereof, a movable bafiie plate mounted across the top of the mill, said baflle plate comprising two hingedly connected sections, means to move the baflle plate through the mill top, means to move the lower edge of one section substantially along the curvature of the throw of the hammers, means to move the upper edge of the other section substantially parallel with the fiow of the fed material,

and a separate air inlet in the mill top to feed air thereto at the opposite side of the baffle from that contacted by the fed material.

3. In a hammer mill including rotating hammers, feed control means in the mill top to obtain suspension grinding for each of various materials fed to the mill top, said control means including a movable bafile in the mill top against which the material is fed, said bafiie comprising two flat sections hingedly connected along abutting edges and mounted in the mill top beyond the throw of the hammers, means to move said bafiie toward or against the fed material, a separate air inlet for the mill top to direct the air therethrough behind said baffle and cooperating means between the free edges of the hinged baffle sections and the mill top to maintain this relationship at any set position of the baffle and during movement of said baffle.

4. In a hammer mill including rotating hammers and a grinding chamber in the top of the mill, a material feed inlet at the top of the mill, a separate air inlet at the top of the mill, a feed control cross baffle movable through the grinding chamber encompassing the entire cross area of the same except for a running clearance between the lower edge of the baflie and the hammers, said bafl le dividing the grinding chamber into a separate section at the base of the material feed inlet and an adjoining separate section at the base of the air inlet, and means for maintaining the divided relationship of the chamber at any set position of the baffle and during movement of the same.

5. In a hammer mill including rotating hammers and a grinding chamber in the top of the mill, a material feed inlet at the top of the mill, a separate air inlet at the top of the mill, a feed control cross battle with a hinged upper portion movable through the grinding chamber encompassing the entire cross area of the same except for a running clearance between the lower edge of the baffle and the hammers, said bafile dividing the grinding chamber into a section connected with the material feed inlet and a section connected with the air inlet, and cooperating means on the baffie and mill top to maintain the divided relationship of the grinding chamber at any set position of the bafile and during movement of the same.

References Cited in the file of this patent UNITED STATES PATENTS 1,200,104 Haskell Oct. 3, 1916 2,145,728 Mankofi Jan. 31, 1939 2,224,442 Mankoff Dec. 10, 1940 2,241,667 Mankotf May 13, 1941 2,609,153 Moore Sept. 2, 1952 

